A stair is a set of steps leading from one floor to another usually inside a building. This is classic definition of a stair. As many things in your house a stair has its own function but it is also a decorative elements, one of the most important because it is usually in a central position in your house and it can be seen by many rooms.
There are many kind of stairs, different styles and a lot of components. Each of them can do a big difference on the style and the result you could have. Let's see all the terminology about stairs
Stairs may be in a straight run, leading from one floor to another without a turn or change in direction. Stairs may change direction, commonly by two straight flights connected at a 90 degree angle landing. Stairs may also return onto themselves with 180 degree angle landings at each end of straight flights forming a vertical stairway commonly used in multistory and highrise buildings. Many variations of geometrical stairs may be formed of circular, elliptical and irregular constructions
The balustrade is the system of railings and balusters that prevents people from falling over the edge.
A term for the vertical posts that hold up the handrail. Sometimes simply called guards or spindles. Treads often require two balusters. The second baluster is closer to the riser and is taller than the first. The extra height in the second baluster is typically in the middle between decorative elements on the baluster. That way the bottom decorative elements are aligned with the tread and the top elements are aligned with the railing angle.
A large baluster or post used to anchor the handrail. Since it is a structural element, it extends below the floor and subfloor to the bottom of the floor joists and is bolted right to the floor joist. A half-newel may be used where a railing ends in the wall. Visually, it looks like half the newel is embedded in the wall. For open landings, a newel may extend below the landing for a decorative newel drop.
A decorative cap to the top of a newel post, particularly at the end of the balustrade.
For systems where the baluster does not start at the treads, they go to a baserail. This allows for identical balusters, avoiding the second baluster problem.
A decorative filler piece on the floor between balusters on a balcony railing.
Handrails may be continuous (sometimes called over-the-post) or post-to-post (or more accurately "newel-to-newel"). For continuous handrails on long balconies, there may be multiple newels and tandem caps to cover the newels. At corners, there are quarter-turn caps. For post-to-post systems, the newels project above the handrails.
Another, more classical, form of handrailing which is still in use is the tangent method. A variant of the Cylindric method of layout, it allows for continuous climbing and twisting rails and easings. It was defined from principles set down by architect Peter Nicholson in the 18th century.